 /*******************************************************************************
  * Copyright (c) 2000, 2005 IBM Corporation and others.
  * All rights reserved. This program and the accompanying materials
  * are made available under the terms of the Eclipse Public License v1.0
  * which accompanies this distribution, and is available at
  * http://www.eclipse.org/legal/epl-v10.html
  *
  * Contributors:
  * IBM Corporation - initial API and implementation
  *******************************************************************************/
 package org.eclipse.ui.texteditor.quickdiff;

 import org.eclipse.core.runtime.CoreException;
 import org.eclipse.core.runtime.IProgressMonitor;

 import org.eclipse.jface.text.IDocument;

 import org.eclipse.ui.texteditor.ITextEditor;


 /**
  * The protocol a reference provider for Quick Diff has to implement. Quick Diff references provide
  * a reference document (an <code>IDocument</code>) that is used as the original against which
  * diff information is generated.
  * <p>Extensions to the extension point <code>quickdiff.referenceprovider</code> have to implement
  * this interface (plus another interface for plug-in and UI management.</p>
  *
  * @since 3.0
  */
 public interface IQuickDiffReferenceProvider {
     /**
      * Returns the reference document for the quick diff display.
      *
      * @param monitor a preference monitor to monitor / cancel the process, or <code>null</code>
      * @return the reference document for the quick diff display or <code>null</code> if getting the
      * document was canceled or there is no reference available.
      * @throws CoreException if getting the document fails.
      */
     IDocument getReference(IProgressMonitor monitor) throws CoreException;

     /**
      * Called when the reference is no longer used and the provider can free resources.
      */
     void dispose();

     /**
      * Returns the id of this reference provider.
      *
      * @return the id of this provider as stated in the extending plugin's manifest.
      */
     String getId();

     /**
      * Sets the active editor for the provider implementation. Will usually just be called right after
      * creation of the implementation.
      *
      * @param editor the active editor.
      */
     void setActiveEditor(ITextEditor editor);

     /**
      * Gives the implementation a hook to publish its enablement. The action corresponding to this
      * implementation might be grayed out or not shown at all based on the value presented here.
      *
      * @return <code>false</code> if the implementation cannot be executed, <code>true</code> if it can,
      * or if it cannot be decided yet.
      */
     boolean isEnabled();

     /**
      * Sets the id of this implementation. This method will be called right after creation, and
      * <code>id</code> will be set to the <code>Id</code> attribute specified in the extension's
      * declaration.
      *
      * @param id the provider's new id.
      */
     void setId(String id);
 }

